Two men have been arrested on suspicion of assault during an English Defence League march to Woolwich, in what they claimed to be a charity walk to Woolwich Barracks where Drummer Lee Rigby was killed last month.
The men are reportedly not from the group.
A Scotland Yard spokesman said:
At approximately 11.25am today, two men were arrested outside Aldgate East station for obstructing police.
They have been taken to a south London police station. Two further men were arrested on suspicion of assault.
They have been taken to an east London police station.